A letter from Einstein to Ludwik Silberstein, a Polish-American physicist, is up for auction online at RR Auction. The letter contains Einstein’s well-known equation E = mc². The letter was written and sent in 1946.
The letter is the only document where E = mc² was handwritten by Einstein that is still in private possession. The estimated value is 400,000 dollars.
The letter is only a page long. In the first part, Einstein already wrote about his formula: “Your question can be answered with the formula E = mc2, without any erudition.
If E is the energy of your system consisting of the two masses, E0 the energy of the masses as they approach an infinite distance, then the mass defect of the system is E0 – E/c2.
In addition to this letter, other letters from Einstein are also sold. In one, he writes about gravitational field equations, in another about Nazism and the rise of Hitler. Bidding starts from 25,000 dollars and can be done on the RR Auction website. The auction ends on May 20.